<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
ul li {
list-style-type: square;
}
li:only-child {
color: blue;
list-style-type: disc;
}
</style>
</head>
<body>
<h2>:only-child selector example</h2>
<ol>
<li>
One element
<ul>
<li>This list has just one element.</li>
</ul>
</li>
<li>
Two elements
<ul>
<li>This list has two elements.</li>
<li>This list has two elements.</li>
</ul>
</li>
<li>
Three elements
<ul>
<li>This list has three elements.</li>
<li>This list has three elements.</li>
<li>This list has three elements.</li>